Breast cancer is the most commonly diagnosed cancer in American women with 209,060 and 54,010 estimated cases of invasive breast cancer and female carcinoma in situ, respectively, in 2010. Approximately 39,840 women will die of breast cancer in the United States in 2010.1
Risk factors for the development of breast cancer can be grouped into categories, including familial/genetic factors (family history, known or suspected BRCA1/2, TP53, PTEN, or other gene mutation associated with breast cancer risk); factors related to demographics (e.g., age, ethnicity/race); reproductive history (age at menarche, parity, age at first live birth, age at menopause); environmental factors (prior thoracic irradiation before age 30 years [e.g., to treat Hodgkin disease], hormone replacement therapy [HRT], alcohol consumption); and other factors (e.g., number of breast biopsies, atypical hyperplasia or lobular carcinoma in situ [LCIS], breast density, body mass index).
Estimating breast cancer risk for the individual woman is difficult, and most breast cancers are not attributable to risk factors other than female gender and increased age. The development of effective strategies for the reduction of breast cancer incidence has also been difficult because few of the existing risk factors are modifiable and some of the potentially modifiable risk factors have social implications extending beyond concerns for breast cancer (e.g., age at first live birth). Nevertheless, effective breast cancer risk reduction agents/strategies, such as tamoxifen, raloxifene, and risk reduction surgery, have been identified. However, women and their physicians who are considering interventions to reduce risk for breast cancer must balance the demonstrated...

Breast cancer is the most frequently diagnosed malignancy in women in the United States and is second only to lung cancer as a cause of cancer death. To assist women who are at increased risk of developing breast cancer and their physicians in the application of individualized strategies to reduce breast cancer risk, NCCN has developed these guidelines for breast cancer risk reduction.